Electrolytic apparatus



Mar. 3. 19215.

w. E. GREENAWALT LECTROLYTIC APPARATUS Filed April 7. 1923 Patented Mar.3, 1%255. I

"WILLIAM E. GREENAWALT, 01E DENVER, COLORADO.

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Application filed April 7,

i To all whom it may concern WALT, a; citizen of the United States,residing in the city an'd county of Denver ,and State of Colorado, haveinvented certain new and useful Improvements in Electrolytic Apparatus,of which the following is a specification.

The apparatus is designed more particularly torthe precipitation orcopper, and the regeneration of ferric salts, in leach solu tions, inprocesses set forth in my pending applications; Serial No. 450,460,filed April 16, 1918: Serial No. 380.361, filed May 10, 1920; and SerialNo. 5202M, filed Decemher 6, 1921, although it is not intended to limitthe apparatus to any particular use.

I It has long been known that in the electrolysis of copper leachsolutions containing salts of iron, effective depolarization prolongsthe lite of the anodes in the deposition of copper and in theregeneration of ferric salts, and, this is the casewhether metal orcarbon anodes are used.

It is possible, under effective depolarization, to use carbon anodes in.the deposition of copper from sulphate solutions;

It has been observed, in precipitating copper from chloride solutions,that under the action of a fairly high current density and. .in thepresence of a. depolarizing agent, such 1 as ferrous sulphate or sulphurdioxide or both, that the copper can be deposited in loose granular formand of high purity, and that this loose granular copper drops from thecathode from time to time, and that the process may be carried onindefinitely, or at least for a considerable time, without removing thecathodes from the cells to strip them of remaining adhering .copper.lVith a chloride solution, carbon anodes are a practical necessity,because metal anodes are very rapidly disintegrated,

while carbon anodes last indefinitely;

Whether chloride or sul hate solutions are used, it is necessary to owthe solution per, and thus greatly reduce the elliciency of thedeposition.

The usoof carbon anodes in copper deposition has always presented adili'icult con struction problem, because the individual 1923. SerialNo. 630,634.

pieces of carbon, from which a complete Be it known that l, l/Vmnmir E.GnnnNA- anode is made, are not very large, and the manufacturing limitof individual pieces 1s about 2 x 8 x48 inches. In assemblii,1g thesepieces to make a complete anode with proper electrical connections, ithas been customary to cast the ends of the pieces in lead. This servedto hold the pieces together and to make electrical connection. Theseanodes are then suspended in the tank, or cell, in the ordinary Way, bymeans of copper rods contacting with the busbars of the cells.

To meet the conditions specified and to the apparatus, showing anenclosed cell.

Referring to the figures, 1 represents a tank adapted to contain theelectrolyte; 2

shows the liquid inlet and 23 the liquid out let, Both the inlet and theoutlet are arranged to distribute the'liquid uniformly across the tank.or cell. 4 are the carbonanodes, which ure supported on longitudinalstrips 5, and these strips arefsupported in turn'bycross pieces 6 in thelower portion of the tank. The bottom of the tank slopes toward a,centrelontlet 3, through which the precipitate, or insoluble material,may be washed from the cell. pieces 6 arepreferebly kept a li le abovethe bottom ofthe tank to facilitate Washing. The longitudinal strips 5are grooved to maintain the bottom of the anodes inf align ment, whileat the same time offering away to support the individual anode pieceswithout costing or joining them together at the top. To make electricalconnection with the anodes, it is preferred to drill a liole in the topof each carbon and insert one end of the conductor rod 8 into the, holeand then pour in moulten lead to secure the rod to the carbon and tomake good electrical connection between the rod and the carbon. The castlead is shown by 10. The rod 8 nay be made of lead or copper. To protectthe rod from attack of the electrolyte at or near the surface, itissurrounded by an insulator 12-, which is slipped over the rod, and whichtill ill

maybe permanently fixedto the rod or made removable. The insulator 12may be made of glass, stoneware, rubber, or the like. I The positiveconductors are. shown by 7 arranged longitudinally with the cell. T heconductor rods 8 of the individual anode.

pieces are secured to the conductors by bolts 9, which may be made astight as'desired to ive good electrical connection. The concauctor rod 8may also be soldered to the con insulator 20.

The cathodes 18, which may beleador copper sheets, are suspended in thetank from the rods 17 and these rods are supported. on,

and make electrical connection with copper -cross bars 16, and the crossbars 16 make electrical connection with the main negative conductor 21at the side of the tank. In or der to save copper, the cross bars 16 aresupported by the cross bars 13. The'bars 13 are preferably madeof aniron bar l-l enclosed or coated with lead 15. Such a bar gives thedesired strength and resists attack from acid fumes or spilled.electrolyte. The connection between the copper bars 16 and the,negatit-veconductor 21 may be made tight y'ith a screw or solder, orboth, as desired,

since the copper bars 16 are more or less permanently positioned untilWorn out. The removable connection is between the rods 17 and the copperbars 16, so that the cathodes 18 may be removed and replaced as desired,with a minimum number of loose connections.- This is of some importance,since much of the energy in'cop'per deposition with the electric currentis consumed by the poor electrical contact with removable connections.Where the cathodes are more or less permanent, as in the presentarrangement, even the cathodes 18 may be soldered to the cross bars 17,to reduce electrical resistance which is due frequently to poorelectrical contact between the cathode and the suspension bar 16.

When gases, such as. sulphur dioxide, are applied. to the electrolyte,or it' there is a corrosive gas liberated as the result of electrolysis,it is preferred to work with a closed celhas shown indiagrammaticsection in Fig. 5. In such cases the electrical contactbetween the suspension rod 17 and the cross bar 16 may be made with aburned or soldered joint. This would always insure good electricalcontact, since the contact would not be effected by corrosive gases. Anexhauster, 24, Working under a slight suction, prevents any gas fromescaping into the cell room and contaminating the atmosphere in thevicinity of the cell.

' A brief description of one Way of operating the apparatus may begiven. If'a copper chloride solution is used as the electrolyte, or say,a copper chloride solution as obtained from leaching ores; it is firsttreated with sulphur dioxide to reduce the cuprio chloride to the.cuprous condition and the' ferric chloride to the /ferrous condition.This reduced solution is then flowed into the apparatus as described,and electrolyzed. With a fairly high current density,- say, from 20 to50 amperes per square foot,

copper is deposited in a somewhat granular form on the cathode, and-thisdeposit accumulates until it becomes too thick to support itself; itthen drops to the bottom of the tank, where it accumulates in a granularform until it 15 desired to remove it. -The chlorine liberated at theanode combines, first with any excess sulphur dioxide and is thusrendered harmless to re-dissolve deposited copper. Similarly, it reactswith the ferrous and cuprous salts before it appreci-- ably attacks thedeposited copper at the cathode, so that practically a theoreticalefiiciency is possible in the deposition ofthe copper, provided theferric and cupric salts are not allowed to accumulate above a certaineconomic limit, bined.

This may be controlled by the rate of flow through the tank or cell. Theissuing electrolyte is then again treated with the gas say 0.25% forboth com-t and returned to the cell, and this-cycle is continued untilthe copper issufiiciently removed from the solution, and then thesolution is returned'to the ore.

To facilitate theflow through the cell, the

electrodes are placed longitudinally with the cell, so that the,electrolyte in flowing through it, contacts all the electrodes andstagnant eddys or pools are avoided. The rate of flow through the cellshould be quite rapid, aild the amount of ferric and-cupric *ltheoutflowlne; solution will deordinarily be necessary toremove any of theelectrodes, under-the assumed conditions.

If, however, a low current density is used,

orit a sulphate solution is used, the copper will accumulate on thecathodes, and then the cathodes have to he removed and stripped, orreplaced, in the usual Way; but even in that case the anodes need not inany way he molested.

Bil

iuisaaos a current. 1500 ampcres flowing through the two outsideconductors and of th) amp-ores flowing; through each of the fourintermodi ate conductors, 7. This current would be delivered tothe cellandelectrolyte, Without any break orremovable joint in the circuit. Ifat any time any of tho anodes should give trouble on account ofcorrosion or regular wear. any individual anode piece may-be. remoyedand replacd by a new one "without intcrforing with the others or withthe operation of. the cell. Any of the cathodes may be removed at anytime without interfering With the operation of the cell. 1 A

The more or less permanent contact between. the loading in metat rods 8and the electric conductors 7, made possible by boltingjor soldering,facilitates thcltransmi sion of large. currents Without any undue,.incre'ass' of resistance at the points of con til) tact.

In the electrolysis of leach copper soluti'onsland in the oxidation offerrous iron. for example, it niay be advisabls to agitate theelectrolyte. lhis agitation-should be mild and should be free from anyunusual mechanical difiicult v in the past. sdcctive agitation. of thoclectrolyte presented great difficulties. Purely mechanical agitation istoo complicated. Air agitation has been usually adopted. but it has beenfound exceedingly diiiicult to apply the air satisfaotorily, especiallyfor mild l1"llftlil0ll. If air is introduccd in (cry small ets in theusual Way. there is danger of the injector becoming clogged, and itintroduced in large jets, much air is wasted, the agitation is tooviolent, and the, air is not eil'ectively atomized and distributed.

I have found that an cxccllcnt way of agitation. as also aeration, is tointroduce the air in moderate size jets or streams, through an injectorso arranged that liquid from the tank flows into the injector by thesuction induced by the air, and a mixture of air and liquid is ejectedfrom the ejector into the surrounding liquid in tho tank. This method oiinjecting the air, breaks the air up into line bubbles. or atomizes it.so that it ascends through the. electrolyte in finely divided and Welldistributed bubbles. Tho injectors are preferably arranged opposite oneanother. so that. streams of gas and liquid issuing from the variousinjectors indicatc an anode current density of 7 ampcrcs per squaretoot, and

will penctratc one another and give a fair ly uniform distribution ofthe gase and a uniform agitation.

in the arrangement shown in the drawings, 26 represents the injectors,taken as a whole. The air or gas pipe in the interior of the injector isshown by 27. the liquid inlet duct by 28, and the injector outlet,through which the gas and liquid are eject-- ed, by 29. The compressedair, or gas, supply main is shown by The compressed gas, forced from themain 25, through the pipe 27, suc zsa portion of the liquid from thetank into the interior of the injector through the ducts Q8, and themixture of gas and liquid is then ejected into the surrounding liquid inthe tank through the outlet 29. The mixture of gas and humid will bedistributed Within a range d ter mined mostly by the pressure of thegas. The gas so ejected will be in a fine state of subdivision. (Thestreams of gas and liquid, from opposite sides of the tank, impinge, orpenetrate one another. so that the finely atomized gas will beevenly'distributed over a large. area, and ascends through the liquidbetween the electrodes. The cfiiciency of tho gas is greatly increased.by this method of applying it. A i

If the gas is air, it simply escapes at the top. If it is some othergas, such as sulphur dioxide, it may be caught in the. hood 22,and'again passed through the electrolyte. until the gas is consumed.form of eXhausten-compressor 24 may be used. The injectors. when used inconnec tion with corrosive liquid or corrosive gases, should be madsofacid resisting material.

' I claim:

1 In electrolytic apparatus, a tank adapted to contain the electrolyte.carbon anodes supported from below arranged longitudinally W. h the tankand making electric contact u'iti longitudinally arranu'cd conductors,an metal cathodes arranged parallel with tho anodes suspended fromlongitudinally a'r-iangcd bars, said bars making elcctrio conthct withconductors arranged transversely of the tank. I

2. In electrolytic apparatus, a tank adapted to contain the electrolyte.electrodes of one polarity supported from bclow and arrangedlongitudinally with the tank and making electric contact withlongitudinally arranged conductors, and electrodes of the oppositepolarity suspended from above and makingelectric cont-act withconductors arranged transversely the ends of the tank.

3. In electrolytic apparatus, a tank adapted to contain'the electrolyte,electrodes of one polarity arranged longitudinall with the tank andmaking electric contact with longitudinal conductors, electrodes of theopposite, polarity arranged longitudinally Any suitable IOU 01" the tankintermediate I tor, said rods without disturbing the others.

with the tank and making electric. contact with conductors arrangedtransversely of the tank intermediate the ends of the tank.

4, In electrolytic apparatus, a tank adapted to contain'tlieelectrolyte, a series of in dividual carbon anode pieces or sectionsarranged longitudinally with the tank to form a composite whole anode,an electric conductor arranged longitudinally with thetank ovcr'thcanode, leading in rods connecting the individual anodepicces with theconducanode piece may be removed and replaced 5. In electrolyticapparatus, a tank edapted to contain the electrolyte, anodes arrangedlongitudinally with the tank and supported from below, electricconductors arranged longitudinally with the tank intermediate its endsover the anodes andsupported on negative cross bar conductors arrangedtransversely or" the tank, and insulators interposed between thepositive and negative conductors at the area of support.

6. In electrolytic apparatus, a tank adapted to contain the electrolyte,positive electrical conductors arranged longitudinally with the tank andInakingelectric contact with a continuous row of anodes within the tank,and negative ranged t its ends cathodes tank.

7. In electrolytic apparatus, a tank adepted to contain the electrolyte,negative electric conductors arrangedtransversely of the tankintermediate its ends, positive. edectric conductors arrangedlongitudinally with the tank and supported by the negative electricconductors, and means for insulating the positive conductors from thenegative condoctors at the points of intersection.

8. In electrolytic apparatus anodes secured in permanent relation to thepositive electric conductor arranged longitudinally with the tank andcathodes arranged in ren'iovable relation 'to the negative electricconductor arranged transversely of the tank.

9. In electrolytic apparatus, a tank adaptcd to contain the electrolyte,anodes secured in permanent relation to the positive l8C' lric conductorarranged longitudinally with the tank, and cathodes arranged'inremovable relation with the negative electric conductor disposedtransversely of the tank intermediate its end.

10. In electrolytic apparatus, a tank adapted. to contain theelectrolyte, electrodes of one polarity supported from below-and makingelectric contact with an electric conransversely of the tankintermediate and making electrie'contact with arranged longitpdinallywith the doctor arranged longitudinally with the tank, and electrodes ofthe opposite polarity suspended from above and making electric beingarranged so that any electric conductors ar essence contact with anelectric transversely of the tank.

I: 11. In electrolytic apparatus, a tank adapted to contain theelectrolyte, electrodes arranged in parallel rows longitudinally withthe tank and making electric contact with conductors arrangedlongitudinally with the tank, said-electrodes being supported frombelow, and means in connection in the lower section arranged in parallelrows longitudinally with the lower section said electrodesbeing'supported' from below, and means for exhausting gas from the uppersection.

14. In electrolytic apparatus, gas injectors in the lower portion of thetank adapted to eject a mixture of gasand liquid in substantiallyhorizontal streams into the surrounding liquid in the tank,said'injectors being arranged so that issuing streams of gas and liquidfrom different injectorswill penetrate one another, plying gas underpressure to said injectors,

15. in electrolytic apparatus, a tank adapted to contain liquid, hollowstationary members in the lower portion of the tank having dischargepassages communicating with agas supply and with the liquid in the tank,means adapted for combining: a stream of gas with a. stream of ii aid insaid'injectors and ejecting the mixture of gas and liquid into thesurrounding: liquid in the tank below the electrodes, and means forsupplying gas under pressure to said hollow stationary members. i

16. In electrolytic apparatus, a tank adapted to contain liquid, hollowstationary members in the lower portion of the tank conductor arrangedsaid conductors being supand means for suphaving discharge passagescommunicating with a gas supply and with the liquid, inthe tank, meansfor supplying gas under pres- Sure to the interior of said hollowstationary members and ejecting the with liquid into the surroundingliquid in the tank below the electrodes, said hollow stationagy membersbeing arranged so that issuing streams of gas and liquid from differenthollow members will penetrate one another.

lVlLLl/Ud E. Gil-ICENAlViU/ll.

